Querying

Mix.install([:ash])

Querying

Data Persistence Home Attributes

In this tutorial you will do basic Query and CRUD operations

But first you need to enable all basic CRUD operations.

Do this by adding the :read, :update and :destroy action to your actions.

Show Solution ```elixir defmodule Tutorial.Profile do use Ash.Resource, data_layer: Ash.DataLayer.Ets actions do defaults [:create, :read, :update, :destroy] end attributes do uuid_primary_key :id attribute :name, :string end end defmodule Tutorial do use Ash.Api resources do resource Tutorial.Profile end end ```

Enter your solution

defmodule Tutorial.Profile do
  use Ash.Resource,
    data_layer: Ash.DataLayer.Ets

  actions do
    defaults([:create])
  end

  attributes do
    uuid_primary_key(:id)
    attribute(:name, :string)
  end
end

defmodule Tutorial do
  use Ash.Api

  resources do
    resource(Tutorial.Profile)
  end
end

Creating

Add 2 Profiles to the database.

• One with the name “Joe Armstrong”
• One with your name

You can create a Profile by:

• Creating a Changeset with Ash.Changeset.for_create(Tutorial.Profile, :create, %{name: "Your Name"}),
• Then giving the changeset to Tutorial.create!().

Hint: Use a pipeline

Show Solution ```elixir Tutorial.Profile |> Ash.Changeset.for_create(:create, %{name: "The Name"}) |> Tutorial.create!() ```

Enter your solution

Reading

Now, read all the generated Profiles.

Call Tutorial.read!/1 with the Tutorial.Profile module.

Show Solution ```elixir Tutorial.Profile |> Tutorial.read!() ```

Enter your solution

Now fetch the “Joe Armstrong” Profile.

You can achieve this by introducing a filter.

First you’ll need to require Ash.Query

Then call Ash.Query.filter(name == "Joe Armstrong") with the Tutorial.Profile.

Put the result into the joe variable. read!/1 returns a list, so make sure to extract the single returned value out of that list.

Show Solution ```elixir require Ash.Query [joe] = Tutorial.Profile |> Ash.Query.filter(name == "Joe Armstrong") |> Tutorial.read!() ```

Enter your solution

You’ll use the joe variable in the next sections.

Updating

Now change Joe Armstrong‘s name to Neil Armstrong.

You can do this by providing the Ash.Changeset.for_update/3 with:

• the resource you want to change, in this case joe
• the :update atom
• a map of the values you want to change, in this case %{name: "Neil Armstrong"}

Then apply the changeset by calling Tutorial.update!/1 with the changeset.

Hint: Using a pipeline might be a good idea.

Show Solution ```elixir joe |> Ash.Changeset.for_update(:update, %{name: "Neil Armstrong"}) |> Tutorial.update!() ```

Enter your solution

Destroying

Finally, remove joe from the database.

Do this using the Tutorial.destroy!/1 function.

Show Solution ```elixir Tutorial.destroy!(joe) ```

Enter your solution

Data Persistence Home Attributes